msm: kgsl: reset GPU when GDSC is forced on

Sometimes for debug purposes the GPU regulators can be left
on, make sure we reset the gpu while waking up.

Change-Id: Ie18c9f45d9f5a5a7587a1bea2c7c9bb5ce000316
Signed-off-by: Suman Tatiraju <sumant@codeaurora.org>